The Florentine statutes, completed in 1409 after fifteen years of preparation, can be considered the most ambitious legislative work in the history of Florence. This study examines their internal features, their relations with previous legislation and the statutes of 1355, and finally the rielaboration of the text by a second commission of jurists in 1415, in order to understand the most important developments of institutional history of the city between the 14th and 15th centuries.